# Gateway tag change issue

**URL:** <https://forum.inductiveautomation.com/t/gateway-tag-change-issue/21697>\
**Category:** Ignition\
**Created:** [January 5, 2019, 12:01am UTC](https://forum.inductiveautomation.com/t/gateway-tag-change-issue/21697 "2019-01-05T00:01:29Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![witman](https://avatars.discourse-cdn.com/v4/letter/w/d2c977/32.png) [@witman](https://forum.inductiveautomation.com/u/witman)\
**Post date:** [January 6, 2019, 10:54pm UTC](https://forum.inductiveautomation.com/t/gateway-tag-change-issue/21697/8 "2019-01-06T22:54:42Z")

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To write each tag from only one direction:

1. PLC sets trigger tag
2. Script runs on trigger tag change, does stuff, and sets handshake tag
3. PLC clears trigger tag when it sees handshake tag
4. Script runs on trigger tag change and clears handshake tag  
This should make a race condition pretty unlikely,

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